I just installed Sage in Linux Mint, and the Import print_function only seems to work in one cell in the Notebook.
If I type this in the top cell it works fine:
from __future__ import print_function
print("all","good","dogs","eat","shoes",sep=" now ")
to print this:
all now good now dogs now eat now shoes
But if I do exactly the same print in the next cell, I get a syntax error.